Tandem anti-lock systems have recently begun to appear on air-braked vehicles. These designs provide a cost effective system while still meeting the performance requirements of FMVSS-121. However, they cannot be universally applied to all vehicles without reservation. This paper discusses possible tandem anti-lock system configurations and factors influencing their application to different vehicle and suspension types. These discussions will be based on computer suspension model studies and vehicle tests. Tandem anti-lock vehicle test data will be shown along with comparisons to axle by axle anti-lock control performance.